| A natural gas liquid recovery device, adopting the expansion refrigeration technology, has appeared a series of problems such as non-conformity product and the apparent decline of product and yield due to the variation of inlet conditions.In this study, aimed at the problems exited in the device, three rehabilitation programs including parameter optimization scheme, DHX tower+downstream double-effect scheme and DHX tower+countercurrent double-effect scheme was proposed. In the parameter optimization scheme, the main operating parameters were optimized without changing process and equipment. In the DHX tower+downstream double-effect scheme, a DHX tower was increased before the deethanizer tower and the former debutanizer was transformed into double effect downstream processes on the base of parameter optimization scheme. Similarly with the former one, the former debutanizer was transformed into double effect countercurrent processes in the DHX tower+countercurrent double-effect scheme. The three schemes wear simulated with HYSYS and the key operating parameters were studied and determined, moreover, the light hydrocarbon yield, production and energy consumption were calculated, respectively.Seen from analysis, under the premise of ensuring product quality, the yield of C3could be respectively increased by6.07%,24.41%and24.41%, the LPG production could be respectively increased by0.96t/d,3.18t/d and3.18t/d, energy consumption per unit product could be respectively reduced by28.04%,45.32%and51.01%for the three schemes. Among them, the countercurrent double-effect scheme showed the highest C3yield and the best energy-saving effect. It is necessary to increase new equipment in the DHX tower+downstream double-effect scheme and the DHX tower+countercurrent double-effect scheme, however, the payback period of the two schemes were lower than the industry benchmark payback period. Above all, the countercurrent double-effect scheme was proposed to be the rehabilitation program. |
